Artificially recharging the Las Vegas Valley (Valley) ground-water system with treated Colorado River water is one water resource management option employed by the Las Vegas Valley Water District (District) to help meet future long-term and short-term peak water demands. The District began operation of an artificial ground-water recharge program in 1988 in order to bank water for future use and to slow declining water levels. Artificial recharge occurs in the winter months, typically from October to May, when there is excess capacity in the Southern Nevada Water System (SNWS), currently a 400 Million Gallon per Day (MGD) treatment and transmission system.
Treated Colorado River water is recharged into the principal aquifer through the District's existing distribution system, to a network of production wells or dual -use wells for both recharge and production. The water is then stored until recovered from the wells, during the high demand summer months. The water recovered is injected Colorado River water, however, this water is accounted against the District's groundwater rights. Credits in the artificial recharge account accrue until needed to cover pumpage in excess of permitted ground-water rights.
Wells used in the program were drilled and constructed in a variety of ways, and have responded differently to artificial recharge operations. The majority of the wells now used for artificial recharge and production were completed prior to 1980, using the cable-tool drilling method, perforated in place and naturally developed. Other wells were installed using the reverse-circulation drilling method with filter packs. The District commenced drilling dedicated injection wells in 1993, to address operational concerns observed in some of the production wells. Several types of installation and drilling methods have been used to optimize injection. The types of drilling methods used for the injection wells include, reverse circulation, air-foam, cable tool and dual-rotary.
In 1988, two dual-use wells where used for production and artificial recharge, injecting an annual total of 1,153 acre feet of water. Since 1988 the artificial recharge program has expanded, using up to 40 wells with eight dedicated injection wells. Total water banked for future use, as of January 1, 1997 is 114,126 acre feet of water. Static water levels in the principal aquifer have risen from 10 to 40 feet in the main area of artificial recharge. Water levels in other areas of the Valley also show increases, indicating that the rise is not isolated, but is occurring throughout the principal aquifer. The artificial recharge program is currently expanding to utilize 31 dual use and 19 injection wells, for a potential capacity of 62,000 gallons per minute of injection or 45,000 acre feet per year of recharge by the fall of 1999.
Artificially recharged groundwater; Colorado River (Colo.-Mex.); Las Vegas Valley (Nev.); Water reclamation; Water treatment
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Las Vegas Valley Water District
Artificial recharge in the Las Vegas Valley: An Operational history.
Available at: http://digitalscholarship.unlv.edu/water_pubs/74
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